Ambulatory health monitoring devices are known in the field of medical instrumentation, in the field of computing, and in the field of wireless sensor networks. Such devices are used for monitoring, recording, and reporting physiological signals. For example, ambulatory health monitoring devices typically include self-test devices such as weight scales for monitoring a user's weight; blood pressure cuffs for monitoring blood pressure; heart rate monitor for monitoring heart rate; temperature sensors for monitoring skin (or core body) temperature; etc.
Wearable devices form a special sub-class of ambulatory monitoring devices. As a group, these have the added advantage that more continuous data can be collected and data can be collected in the subject's [more] natural environment. Holter monitors for ECG and EEG monitoring are among the first and most frequently used wearable devices. Current devices are limited, however, in that they are strictly data acquisition devices. Data is typically retrieved and analyzed post recording session.
When the devices are wirelessly enabled, they are also in the field of wireless sensor networks (WSNs). WSNs are comprised of one or more sensor nodes and a system controller. Sensor nodes include a computing platform with wireless communication capabilities and one or more sensor devices. The system controller provides a data sync point for the collection and extraction of data, system configuration capabilities, and may include an interface for the end user of the wireless sensor network. The system controller may be referred to as a personal server, network coordinator or personal area network (PAN) coordinator. The system controller may provide visual, audible or other signals to the user in response to certain events.
Another category of health monitoring device includes the so called Personal Emergency Response System (PERS) devices. They are wearable, but strictly speaking are not monitoring any health information. Instead, they are an active alert response system. That is, the user must press an emergency button to notify the monitoring center of an event. This is intended for situations such as when the user falls and needs outside assistance especially suited for independently living elderly adults. These systems have the distinct disadvantage that they require active participation from a user to be effective.
Certain measures of a user activity are often considered important and relevant to the field of interest, but are not all available by current state of the art devices. These are defined herein: Fall Detection refers to the passive detection (no button requires pressing) of a user falling down. Step Detection refers to the systematic detection of steps as well as recording number of daily steps. Orientation or posture refers to whether the user is horizontal or vertical. Category of Activity, for purposes within, refers to whether the user is resting, standing/sitting, walking, or fast walking/running. Sleep/Wake patterns refer to more general categories of activity (sleeping or not sleeping). Levels of Activity refer to any quantitative measure of activity such as caloric expenditure or some other relative units for measuring activity.